The overall goal of this research is to examine the potential of using hyperpolarized gases (Helium & Xenon) for in vivo imaging of air spaces of the normal and diseased lung. MR microscopy has many advantages. Perhaps the most significant is to non-invasively image the live, small animal at microscopic dimensions. Currently, we are able to routinely image the proton or water containing substances of organs and tissues down to 20-30 microns. However, in the case of the lung, we are able to image it with MR with difficulty and only because it has water containing structures conveniently interspersed within it. With hyperpolarized He or Xe gas introduced into the lung, we will be able to image and measure the airspaces of the lung directly. Such capability has enormous potential in animal research of disease models especially for emphysema and asthma. The ability to follow non-invasively in vivo the progression and regression of disease with MR has revolutionized modern diagnosis and therapy. The Center for In Vivo Microscopy is an NIH-funded National Resource charged with extending the application of MR imaging to the microscopic domain and making the tool available to a wide range of basic scientists. The work proposed here will apply directly to models of lung disease. The lung represents a particularly challenging organ system for MR microscopy due to the very limited signal in the lung because of its low density and the constant motion from breathing and cardiac pulsation. Recent work at the Center have demonstrated solutions to both these problems yielding the highest resolution images yet obtained in vivo of the lung. Recent advances in He and Xe gas imaging provide new and exciting possibilities for lung imaging. The techniques propose here will further extend the resolution as well as yield three-dimensional morphometry.